Mole plough linkages

ABSTRACT

A linkage arrangement for coupling a soil-working implement to a traction vehicle by first and second interconnected supporting members therebetween, the first and second members being relatively movable transversely of the linkage and controlled in said relative movement by constraining follower means comprising at least one roller movable transversely of the linkage relative to each of the supporting members.

United States Patent 1191 Long [ MOLE PLOUGH LlNKAGES [75] Inventor: Terence Long, Leeds, England [73] Assignee: Hudswell Yates Developments Limited, Leeds, England 221 Filedz June 11, 1973 21 Appl. No: 369,080

[30] Foreign Application Priority Data Feb. 19,1973 llgLdlQrgdom 8126/73 [52] U.S. C1 403/121, 37/193, 172/699, 403/82, 403/163 [51] 1111.01. ..B25g 3/38 [58] Field of Search 403/121, 82, 163, 80,75,

[ Mar. 18, 1975 [56] References Cited UNITED STATES PATENTS 3,032,903 5/1962 Ede 172/699 X Primary ExaminerH. Hampton Hunter Attorney, Agent, or FirmMerriam, Marshall, Shapiro & Klose [57] ABSTRACT A linkage arrangement for coupling a soil-working implement to a traction vehicle by first and second interconnected supporting members therebetween, the first and second members being relatively movable trans versely of the linkage and controlled in said relative movement by constraining follower means comprising at least one roller movable transversely of the linkage relative to each of the supporting members.

13 Claims, 8 Drawing Figures PATENTEB HAR I 81975 FIG.

MOLE PLOUGH LINKAGES The present invention relates to linkages for supporting and controlling rear-mounted soil-working implements on traction vehicles such as tractors. In particular, the invention relates to such linkages which have a so called floating action".

The progression from a rigidly-mounted implement to one with a floating action now will be described with reference to FIGS. 1 to 6 of the accompanying drawings, in which FIGS. 1 to 3 show diagramatically the systems of forces acting on various arrangements of a tractor and an associated rigidly-mounted implement, FIG. 4 shows a system of forces acting if the attachment is changed from a rigid one to one in which the implement is pivotally attached, while FIGS. 5 and 6 illustrate the forces acting in a particular pivotal attachment.

With reference to FIG. 1, the resultant soil-force S at the implement is shown as acting horizontally below the surface; the tractive force T acting approximately along the surface, forming a couple with force S. This couple is reacted by the tractor weight W and the vertical track reaction R.

It can be seen that, if W acts near the centre of the track, then R must be appreciably displaced from the centre. The result, in practice, would be that the tractor would tend to adopt a nose-down attitude and local track pressure would be increased, in each case performance being degraded.

In FIG. 2, the soil-force S has been inclined so as to pass through the point of intersection of T and W by modifying the shape of the implement, for example, by providing an inclined upper surface as shown. With this arrangement, the track reaction R must pass through the same point as the other forces and can now be close to the centre of the tracks. The result is less tendency for the tractor to be up-ended, and a lower, more uniform track pressure.

In practice, the centre of gravity of the combined tractor and implement is likely to be positioned to the rear of the centre of the tracks, and therefore the soilforce S needs to be less steeply inclined, as shown in FIG. 3, for the track reaction R to be centrally disposed along the track length. There is an additional advantage in reducing the inclination of S, since a reduction in the vertical component of S tends to reduce the magnitude of the track reaction R.

If now the implement attachment is changed from a rigid one to one in which the implement is pivotally attached at point A, as shown in FIG. 4, then (ignoring the small effect of couples arising at the implement itself) the arrangement is in equilibrium with the same force arrangement as in FIG. 3.

By suitably designing the implement, the arrangement shown in FIG. 4 can be made to have a natural stability so that it tends to maintain an equilibrium implement depth relative to point A when drawn through the ground. Such an arrangement is deemed to have a floating action and is in common use on mole ploughs of the floating-beam type.

From a practical viewpoint, the arrangement of FIG. 4 has serious disadvantages in that physically locating the pivot mechanism at point A in a suitable position may be inconvenient, and the structure required to attach the implement to the pivot at A is long and must be designed so as to avoid interference with the tractor structure.

In view of these disadvantages, improvements have been made, such as those described in British patent specification No. 851746. The kinematic analogue of the pivot at A is theoretically achieved by means of a roller and guide arrangement; a roller being fixed on one of a pair of supporting members and located in a guide track of the other supporting member to constrain the implement to move in an arc centred on a point such as A. By this means the need for a structure connecting the implement to A and the problem of locating the pivot itself are avoided. Thus, the attachment of the implement to the tractor can be made at the tractor backplate.

As mentioned above, the arrangement of FIG. 4 (or its Kinematic analogue described in the patent referred to) has a tendency to maintain an equilibrium implement depth relative to point A; the point A being the effective hitch-point. It follows that vertical movement of the effective hitch-point will result in a corresponding tendency for changes in the implement depth as the tractor moves along the surface. This attribute can be used to control the implement depth to a space-fixed reference line by counteracting disturbances caused, for example, by the tractor moving over uneven ground. The necessary control action is that of raising or lowering the effective hitch-point. Such control is of particular advantage where the implement is a mole plough or a similar drain laying device which must be accurately controlled to grade.

A suitable way of adjusting effective hitch-point height in combination with the roller and guide arrangement of British specification No. l 746 is to employ the type of quadrilateral linkage system also described in that specification but used elsewhere, for example, on ripping implements.

In its general application to rear-mounted soilworking implements, an arrangement such as that described, with a floating action produced by a roller and guide layout, and a means for adjusting the effective hitch-point height has distinct advantages compared to those lacking such a floating action. It provides a de gree of de-coupling between the tractor and imple ment, allowing the implement depth to be controlled in the presence of disturbing influences arising, for example, from terrain undulations or changing soil characteristics, and also permitting a predictable balance of forces on the tractor which enables it to operate to good advantage.

Two practical examples will be quoted to illustrate the concepts range of applicability. The first is a mole plough or similar drain laying device where the simplest floating action arrangement with a fixed effective hitch-point height smooths the effect on the line of the drain or mole tunnel of disturbances caused by pitching or heaving of the tractor. By control of the effective hitch-point position on the tractor, the line of the drain can be smoothed even more. The second is a ripper mounting, where maintenance of a precise depth is not generally required, although there is particular value in minimising any upsetting couple on the tractor due to force variations at the ripping blade, so that the tractor can exert the higher draw-bar pull possible with a more uniform track pressure.

The arrangement described in British specification No. 851746 suffers from the practical disadvantage since the effect of friction arising at the pivots of the pivotally-attached rollers means that, although a kinematic analogue of a beam pivoted at point A (FIG. 4), the arrangement is not a true dynamic analogue. Thus, the effective hitch-point is at the intersection of the resultants R, and R acting at each of the roller/guide interfaces (FIGS. 5 and 6). The intersection point P moves away from the Kinematic hitch-point K in a direction dependent upon the direction of the forces F due to friction, that is, which way the rollers 8 are rolling relative to the guide track 9 and a distance which is a function of the relative magnitude of forces F and S. There are two serious drawbacks resulting from friction. The first is the movement of the effective hitchpoint P, which severely reduces the degree of decoupling between tractor and implement. The second results from the fact that, at high drawbar pulls where forces 8, and S, are large, forces F and F, can be so large that the rollers do not roll; the result being that the implement is lifted or forced down in the ground exactly as though it were rigidly connected to the tractor; that is, the floating action is lost.

One method of reducing the effects of friction is the improvement proposed in co-pending US. patent application Ser. No. 366,962 filed June 4, 1973. A further solution is provided by the present invention which seeks to make possible a more truly dynamic analogue as well as a kinematic analogue of the arrangement shown in FIG. 4 by avoidance of any pivotally fixed rollers and the consequent elimination of the associated frictional forces.

In one aspect of the present invention there is provided a linkage comprising a pair of supporting members each provided with a roller guide means, and at least one roller member mounted for movement relative to each of the supporting members. Thus in this arrangement, instead of the floating action being produced by a track, or tracks, in one supporting member and corresponding follower roller members pivotally attached to the other supporting member, the supporting members can move relative to each other and relative to the roller member; there being certain geometric constraints to the relative positions of the roller members and the supporting members.

By this means, the need for pivotal bearings is eliminated and thus the associated frictional effects no longer arise.

In order that the invention may be more readily understood, an embodiment thereof, given by way of example only, now will be described with reference to the accompanying drawings, in which:

FIG. 7 shows, in side elevation, a mole plough linkage according to the present invention; and

FIG. 8 is a sectional view on line VIII-VIII in FIG. 7.

With reference to FIGS. 7 and 8 there is shown a linkage system 10 for providing a support linkage between a traction vehicle and a mole plough, including first and second supporting members 12, 14. The first supporting member 12, as shown, is pivotally secured by pins to a first unit in the form of a pair of generally parallel rigid links 18, 20, secured at their forward ends to vertically spaced pivot points on a traction vehicle (not shown). The first support member forms the rear end of a parallel motion supporting linkage 16 which includes links 18, 20.

The second support member 14 is rigidly mounted on a second unit in the form of a blade, the mole plough part of which is indicated at 22; the member 14 comprising a pair of parallel plate portions 24 between the forward edges of which the trailing edge of the first supporting member 12 is received and movably held. As evident from a consideration of FIGS. 7 and 8, the first supporting member is held between the plate portion 24 of the second supporting member by a roller and track arrangement. Each of the members, 12, 14 is provided with corresponding elongated aperatures or upper tracks 25, 26 and elongated apertures or lower tracks 27, 28, respectively, which are held in a aligned relationship by upper and lower rollers 29, 30 extending therethrough. On the outer faces of plate portions 24 are mounted roller supports 32, each of which extends across a respective one of the openings defining upper and the elongated aperatures lower tracks 26 and 28. Each roller support 32 has an inwardly directed projection 33 on which the rollers are journalled. The assemblies of the rollers and roller supports are nonrigidly fixed relative to the support members by means of pins 34, 35 mounted on the first and second support members, respectively, which are slideably engaged in slots in the ends of roller supports 32. The non-rigid mounting of the rollers and roller supports is such that with relative vertical movement between the first and second support members, the rollers are constrained so as to occupy a position intermediate the ends of the respective aligned upper and lower tracks.

If all of the tracks are co-axial and have the same radius of curvature, then the blade and mole will, in use, be geometrically constrained to move as though attached to a rigid beam pivoted at the centre of curvature of the tracks. Variation from a common, constant, radius of curvature for all tracks may be desirable. For example, straight tracks may afford an adequate approximation to the action of curved tracks while being simpler to manufacture. Similarly, other combination of track shapes may be utilised to vary the ratio of relative vertical movement to relative angular movement existing between the supporting members having the tracks, thus giving the mole plough different stability characteristics in its grading action. These track shapes may also be simply adjustable by using alternative inserts of suitable profiles, for example, by replacing the track surface by one of a different profile.

Unlike the previous systems referred to, the rollers of the present invention are not rigidly attached to either of the support members. Nevertheless, they must by supported such as by the roller supports described so that they do not simply occupy a position at the bottom of the roller track, but are constrained to appropriate positions relative to the tracks.

It will be appreciated that in the arrangement illustrated movement of one supporting member relative to the other is double that of the roller relative to either track. Thus, it is sufficient to constrain the centre of the roller to lie always mid-way between a particular point on each supporting member, as attained by the use of the simple roller supports illustrated. The journalling of the rollers on projections of the roller supports does not introduce unwanted friction effects since it is not transmitting high forces.

It also will be appreciated that the parallel motion supporting linkage 16 can be provided with a ram extending diagonally thereof to permit variation in the lengths of the diagonal and so permit raising and lowering of the first support member and provide a grading action for the mole plough.

What is claimed is:

1. A linkage arrangement for connecting first and second units comprising:

a first supporting member adapted to be secured to said first unit;

a second supporting member movable relative to the first supporting member and adapted to be secured to said second unit; and

constraining follower means for controlling said relative movement; the follower means comprising at least one roller, and for each roller, roller support means pivotally connected to said first supporting member and said second supporting member and supporting its respective roller for movement transversely of the linkage arrangement relative to each of the first and second supporting members upon said relative movement.

2. A linkage arrangement according to claim 1 wherein at least one of said supporting members is provided with bearing surfaces along which said roller is movable.

3. A linkage arrangement according to claim 2 wherein said bearing surfaces are defined by an elongate aperture in said at least one supporting member extending in the direction of relative movement of its supporting members.

4. A linkage arrangement according to claim 3 wherein the elongated aperture includes opposed bearing surfaces on opposite sides thereof, said bearing surfaces having a common centre of curvature.

5. A linkage arrangement according to claim 3 wherein the elongated aperture includes opposed bearing surfaces on opposite sides thereof, said bearing surfaces being in a parallel, substantially linear relationship.

6. A linkage arrangement according to claim 1 wherein there are at least two said rollers.

7. A linkage arrangement according to claim 6,

wherein at least one of said supporting members is provided with bearing surfaces along which said rollers are movable, said bearing surfaces being defined by an elongate aperture in said at least one supporting mem- 5 ber extending in the direction of relative movement of said supporting members.

8. A linkage arrangement according to claim 6, wherein at least one of said supporting members is provided with bearing surfaces along which said rollers are movable, said bearing surfaces being defined for each roller by a respective elongate aperture in said at least one supporting member, said elongate apertures being substantially longitudinally spaced in the direction of relative movement of said supporting members.

9. A linkage arrangement according to claim 1, wherein the first supporting member includes a pair of spaced, substantially parallel plate members between which the second supporting member is received, said at least one roller extending between said parallel plate members.

10. A linkage arrangement according to claim 9, wherein there are two said rollers each movable in a respective one of a pair substantially longitudinally spaced elongate apertures in said second supporting member.

11. A linkage arrangement according to claim 10, wherein each of said plate members is provided with a pair of substantially longitudinally spaced elongate apertures, each of which apertures is at least partially coextensive with a respective aperture of said second supporting member.

12. A linkage arrangement according to claim 2 wherein said roller support means maintain said at least one roller intermediate the remote ends of the bearing surface along which it is movable.

13. A linkage arrangement according to claim 1 wherein said roller support means comprises a pair of support members between which said at least one roller is journalled. 

1. A linkage arrangement for connecting first and second units comprising: a first supporting member adapted to be secured to said first unit; a second supporting member movable relative to the first supporting member and adapted to be secured to said second unit; and constraining follower means for controlling said relative movement; the follower means comprising at least one roller, and for each roller, roller support means pivotally connected to said first supporting member and said second supporting member and supporting its respective roller for movement transversely of the linkage arrangement relative to each of the first and second supporting members upon said relative movement.
 2. A linkage arrangement according to claim 1 wherein at least one of said supporting members is provided with bearing surfaces along which said roller is movable.
 3. A linkage arrangement according to claim 2 wherein said bearing surfaces are defined by an elongate aperture in said at least one supporting member extending in the direction of relative movement of its supporting members.
 4. A linkage arrangEment according to claim 3 wherein the elongated aperture includes opposed bearing surfaces on opposite sides thereof, said bearing surfaces having a common centre of curvature.
 5. A linkage arrangement according to claim 3 wherein the elongated aperture includes opposed bearing surfaces on opposite sides thereof, said bearing surfaces being in a parallel, substantially linear relationship.
 6. A linkage arrangement according to claim 1 wherein there are at least two said rollers.
 7. A linkage arrangement according to claim 6, wherein at least one of said supporting members is provided with bearing surfaces along which said rollers are movable, said bearing surfaces being defined by an elongate aperture in said at least one supporting member extending in the direction of relative movement of said supporting members.
 8. A linkage arrangement according to claim 6, wherein at least one of said supporting members is provided with bearing surfaces along which said rollers are movable, said bearing surfaces being defined for each roller by a respective elongate aperture in said at least one supporting member, said elongate apertures being substantially longitudinally spaced in the direction of relative movement of said supporting members.
 9. A linkage arrangement according to claim 1, wherein the first supporting member includes a pair of spaced, substantially parallel plate members between which the second supporting member is received, said at least one roller extending between said parallel plate members.
 10. A linkage arrangement according to claim 9, wherein there are two said rollers each movable in a respective one of a pair substantially longitudinally spaced elongate apertures in said second supporting member.
 11. A linkage arrangement according to claim 10, wherein each of said plate members is provided with a pair of substantially longitudinally spaced elongate apertures, each of which apertures is at least partially co-extensive with a respective aperture of said second supporting member.
 12. A linkage arrangement according to claim 2 wherein said roller support means maintain said at least one roller intermediate the remote ends of the bearing surface along which it is movable.
 13. A linkage arrangement according to claim 1 wherein said roller support means comprises a pair of support members between which said at least one roller is journalled. 